Vehicle floor production system

ABSTRACT

In one aspect, the present invention provides a vehicle floor production system, in which a carrier is moved through a loop formed by a return line provided at the top of the system and a welding line provided at the bottom, and the carrier is horizontally moved by the frictional force of a horizontal movement driving means. Preferred systems can reduce the manufacturing cost and required installation area.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) the benefit of KoreanPatent Application No. 10-2008-0031400 filed Apr. 3, 2008, the entirecontents of which are incorporated herein by reference.

BACKGROUND

(a) Technical Field

The present invention relates to a vehicle floor production system. Moreparticularly, the present invention relates to a vehicle floorproduction system, in which a working line is disposed at the bottom ofthe system and a return line is disposed at the top so as to ensuresafety and working space.

(b) Background Art

As shown in exemplary FIG. 1, a conventional front floor 100 forming anengine room 101 of a vehicle in general includes a dash panel 110, leftand right fender apron members 112 and 113, and a radiator supportmember 114. The dash panel 110 serves as a partition between the engineroom and a passenger room and prevents noise and vibration from beingintroduced into the passenger room. The left and right fender apronmembers 112 and 113 are butt-welded at predetermined regions of left andright sides of the dash panel 110 so that the front portions thereofextend toward the vehicle front. Accordingly, the left and right fenderapron members 112 and 113 support left and right side portions of theengine and a transmission and fix the upper part of a strut of a frontsuspension. Both side portions of the radiator support member 114 arebutt-welded to the front surfaces of the left and right fender apronmembers 112 and 113 so as to support the structure of a cooling systemincluding an air conditioner and a radiator.

The above-described panel and members (hereinafter referred to as apanel) are welded to each other to form the front floor 100.

Exemplary FIG. 2 is a configuration diagram showing a conventional frontfloor production system which generally comprises a linear motor 121, astopper 122, a carrier 123, a turntable 124, a welding robot 125, and anunloading robot 126.

In the conventional front floor production system, the carrier 123 thatrestricts the panel is moved using the linear motor 121 in a non-contactmanner and is rotated by the turntable 124 in a welding process. Aftercompletion of the welding process, the panel is unloaded from thecarrier 123 by the unloading robot 126 and transferred to the followingline. Accordingly, the stopper 122 stops the carrier 123 at a desiredposition during transfer to the following line, thus regulating theposition of the carrier 123.

The operation order of the system having the above-describedconfiguration is described below.

(1) The panel is loaded on the carrier 123 in process-A, and the carrier123 is transferred to process-B.

(2) When the turntable 124 is rotated, the carrier in process-B istransferred to process-C and subjected to the welding process, and thecarrier 123 of process-C is returned to process-B so that the unloadingrobot 126 unloads the panel from the carrier 123.

(3) The carrier 123 of process-D is transferred to process-A so thatanother panel is loaded thereon.

(4) The carrier 123 of process-B after completion of unloading istransferred to process-D to stand by.

In the conventional linear motor, since the number of the linear motorsis large, the manufacturing cost is suitably increased and, since thecapacity of inverters for controlling the motors is increased, themanufacturing cost is further increased and the size of a control panelthat is needed is thus increased. Accordingly, with the increase in thecontrol panel, the installation area is also increased.

Moreover, in the case of an inverter-type linear motor, a stopper isneeded during stop, and an impact absorbing means is used to reduceimpact force during stop, which is consumable and unfavorable forpreservation, and thus causes a cost increase.

Furthermore, since the linear motor is driven in a non-contact manner,an error in speed control frequently occurs and, in order to maintain agap between the linear motor and the carrier, the manufacturing andassembling costs are increased.

In addition, because a process has to be added every time a vehicle typeis added, the system operation is restrictive, and the manufacturingcost of the turntable is high.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY

In one aspect, the present invention is directed to a vehicle floorproduction system, in which a carrier is moved through a loop formed bya return line provided at the top of the system and a welding lineprovided at the bottom, and the carrier is horizontally moved by thefrictional force of a horizontal movement driving means, such preferredsystems can reduce the required manufacturing cost and installationarea.

In one embodiment, the present invention provides a vehicle floorproduction system, in which the carrier is handled by a carrier changingrobot, and thus a carrier loading stand of the system does not requireany separate device for handling the carrier, thus contributing tosimplification of the system.

In another embodiment, the present invention provides a vehicle floorproduction system comprising: a return line and a welding line providedparallel or substantially parallel to each other on the top and bottomof a frame so as to move a carrier; a carrier drop means including aguide rail provided on the top thereof to load a panel on the carrierreceived from the return line and move the carrier to the welding line;a horizontal movement driving means for moving the carrier in thehorizontal direction on the return line, the welding line and thecarrier drop means by frictional force; a welding robot for welding thepanel moved by the horizontal movement driving means in a predeterminedsection of the welding line; and a carrier changing robot including acarrier handling hanger provided at an end of an arm portion thereof tomove the carrier from the welding line to the return line aftercompletion of the panel welding process.

In another preferred embodiment, the return line and the welding lineinclude first and second driving wheels provided to move the carrier,and a portion of the first driving wheel of the return line is movedupward and mounted to ensure a working space of a welding robot.

In still another preferred embodiment, the carrier drop means comprises:a frame including a guide rail provided on the top thereof; a verticalcolumn for supporting the frame to slidably move in the up and downdirection; a horizontal column for connecting the top portion of thevertical column; an up-and-down movement motor provided on the top ofthe horizontal column; a power transmission means for transmitting therotational force of the up-and-down movement motor to the frame; and aweight balance connected to an end portion of the power transmissionmeans and moving up and down at the opposite side of the frame toadjusting the balance.

In still another preferred embodiment, the power transmission meanscomprises: a rotation transmission shaft connected to an output shaft ofthe motor and including a pulley provided on the outer surface thereof;and a belt, of which one end is connected to the frame and a middleportion is engaged with the pulley so as to transmit the rotationalforce of the motor.

In yet another preferred embodiment, the horizontal movement drivingmeans comprises: a friction bar fixedly provided in the longitudinaldirection of the carrier; a horizontal movement motor and a deceleratorprovided on the frame on which the carrier drop means, the return line,and the welding line are provided; a friction wheel driven by thehorizontal movement motor and the decelerator and transmitting therotational force of the motor by being contact with one side of thefriction bar; a guide wheel rotatably provided on both sides of thefriction bar to be in contact therewith; and an idle wheel provided onthe opposite side of the friction bar to be in contact therewith.

In still yet another preferred embodiment, the horizontal movementdriving means further comprises: a hinge pin rotatably supported to theframe; first and second rotational members, of which center portions arerotatably connected to the hinge pin; and a gap adjusting bolt and aspring inserted between end portions of the first and second rotationalmembers, wherein the motor, the decelerator, and the friction wheel areprovided on one side of the first rotational member, and the idle wheelis provided on one side of the second rotational member, and wherein thefriction wheel and the idle wheel are in frictional contact with thefriction bar by the elastic force of the spring, and a gap between thefirst and second rotational members is adjusted by the gap adjustingbolt.

In a further preferred embodiment, the system further comprises acarrier loading stand capable of loading carriers classified by vehicletype, wherein the carrier loading stand includes a vertical frameprovided in the vertical direction and a loading frame provided in thehorizontal direction on the top and bottom thereof, and a carrier of thewelding line and a carrier of the carrier loading stand are changed bythe carrier changing robot.

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like.

The above features and advantages of the present invention will beapparent from or are set forth in more detail in the accompanyingdrawings, which are incorporated in and form a part of thisspecification, and the following Detailed Description, which togetherserve to explain by way of example the principles of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will now bedescribed in detail with reference to certain exemplary embodimentsthereof illustrated by the accompanying drawings which are givenhereinafter by way of illustration only, and thus are not limitative ofthe present invention, and wherein:

FIG. 1 is a perspective view showing a conventional front floor formingan engine room of a vehicle.

FIG. 2 is a configuration diagram showing a conventional front floorproduction system.

FIG. 3 is a configuration diagram showing a front floor productionsystem in accordance with a preferred embodiment of the presentinvention.

FIG. 4 is a front view of a welding line and a return line of FIG. 3.

FIG. 5 is a configuration diagram showing a drop lifter of FIG. 3.

FIG. 6 is a configuration diagram showing a horizontal movement drivingmeans of FIG. 3.

FIG. 7 is a perspective view showing a state where a friction bar isattached to a carrier of FIG. 3.

FIG. 8 is a rear view of FIG. 7.

FIG. 9 is a side view showing a working state of a welding robot of FIG.3.

FIG. 10 is a configuration diagram showing a welding section of FIG. 3.

FIG. 11 is a diagram showing an unloading section and a carrier changingrobot.

FIG. 12 is a perspective view showing a carrier loading stand.

Reference numerals set forth in the Drawings includes reference to thefollowing elements as further discussed below:

10: drop lifter 11: horizontal movement driving means 12: carrier 13:carrier loading stand 14: unloading robot 15: carrier changing robot 16:welding robot 17: welding line 18: return line 19: guide rail 20:up-and-down movement frame 21: first driving wheel 22: electricity andair supply 23: vertical column 24: horizontal column 25: connectionframe 26: up-and-down movement motor 27: timing belt 28: weight balance29: guide roller 30: decelerator 31: induction motor 32: friction wheel33: idle wheel 34: friction bar 35: first member 36: second member 37:hinge pin 38: spring 39: bolt 40: nut 41: first driving rail 42: seconddriving rail 43: jig unit 44, 56: fixing pin 45: frame 46: verticallyextending frame 47: arm 48: second driving wheel 49: carrier changingrobot 50: carrier handling hanger 52: guide wheel 53: stopper 54:vertical frame 55: horizontal frame

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of theinvention. The specific design features of the present invention asdisclosed herein, including, for example, specific dimensions,orientations, locations, and shapes will be determined in part by theparticular intended application and use environment.

DETAILED DESCRIPTION

As described herein, the present invention includes a vehicle floorproduction system comprising a return line and a welding line to move acarrier, a carrier drop means, a horizontal movement driving means, anda welding robot for welding the panel moved by the horizontal movementdriving means in a predetermined section of the welding line.

In certain embodiments, the vehicle floor production system furthercomprises a carrier changing robot including a carrier handling hangerprovided at an end of an arm portion thereof to move the carrier fromthe welding line to the return line after completion of the panelwelding process. In other embodiments, the horizontal movement drivingmeans moves the carrier in the horizontal direction on the return line,the welding line and the carrier drop means by frictional force. Inother embodiments, the return line and a welding line provided parallelor substantially parallel to each other on the top and bottom of a frameso as to move a carrier. In still further embodiments, the carrier dropmeans includes a guide rail provided on the top thereof to load a panelon the carrier received from the return line and move the carrier to thewelding line.

The invention also includes a motor vehicle comprising the vehicle floorproduction system as described in any of the aspects herein.

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the drawingsattached hereinafter, wherein like reference numerals refer to likeelements throughout. The embodiments are described below so as toexplain the present invention by referring to the figures.

Exemplary FIG. 1 is a perspective view showing a conventional frontfloor forming an engine room of a vehicle, FIG. 2 is an exemplaryconfiguration diagram showing a conventional front floor productionsystem, FIG. 3 is an exemplary configuration diagram showing a preferredfront floor production system in accordance with a preferred embodimentof the present invention, exemplary FIG. 4 is a front view of a suitablewelding line and a suitable return line of FIG. 3, exemplary FIG. 5 is aconfiguration diagram showing a suitable drop lifter of FIG. 3,exemplary FIG. 6 is a configuration diagram showing a suitablehorizontal movement driving means of FIG. 3, exemplary FIG. 7 is aperspective view showing a state where a friction bar is attached to acarrier of FIG. 3, exemplary FIG. 8 is a rear view of FIG. 7, exemplaryFIG. 9 is a side view showing a working state of a suitable weldingrobot of FIG. 3, exemplary FIG. 10 is a configuration diagram showing awelding section of FIG. 3, exemplary FIG. 11 is a diagram showing anunloading section and a carrier changing robot, and exemplary FIG. 12 isa perspective view showing a carrier loading stand.

A front floor production system in accordance with a preferredembodiment of the present invention suitably comprises a drop lifter 10(carrier drop means), a horizontal movement driving means 11, a carrier12, a carrier loading stand 13, an unloading robot 14, a carrierchanging robot 15, and a welding robot 16.

In certain embodiments according to the present invention, a weldingline 17 and a return line 18 are suitably independently provided inconsideration of production and working stability. Preferably, thewelding line 17 is suitably provided at the bottom of the system and thereturn line 18 is suitably provided at the top such that the carrier 12is circulated through the welding line 17 and the return line 18 for thefront floor production.

Preferably, the drop lifter 10 is an up-and-down movement means fordropping the carrier 12. Accordingly, the drop lifter 10 receiving thecarrier 12 returned to the return line 18 preferably moves down totransfer the carrier 12 to the welding line 17 and then is suitablyreturned to the original position.

Preferably, the drop lifter 10 comprises an up-and-down movement frame20 including guide rails 19 suitably formed parallel or substantiallyparallel to each other on the top thereof, a support means for suitablysupporting the up-and-down movement frame 20 so as to move up and down,and a carrier drop means and a power transmission means, provided on thesupport means to suitably move the up-and-down movement frame 20 in theup and down direction.

In one embodiment of the invention, the guide rails 19 are preferablyprovided on the top of the up-and-down movement frame 20 so that a firstdriving wheel 21 of the carrier 12 returned along the return line 18 maymove along the guide rails 19. In certain examples, the up-and-downmovement frame 20 has a lattice structure including a plurality ofvertical members suitably formed parallel to each other in thelongitudinal direction thereof and a plurality of horizontal memberssuitably formed in the width direction to substantially connect thevertical members.

In further embodiments, a horizontal movement driving means 11 forhorizontally moving the carrier 12 is suitably provided in or near themiddle of the up-and-down movement frame 20 so as to transfer thecarrier 12, and an electricity and air supply 22 is preferably providedon one side of the guide rail 19 in the width direction so as tosuitably supply electric power and air to the carrier 12.

Preferably, the support means includes two vertical columns 23 suitablypositioned on one side of the up-and-down movement frame 20 to supportthe up-and-down movement frame 20 so as to move up and down, and ahorizontal column 24 suitably connecting the upper portions of thevertical columns 23.

In other embodiments, the lower portions of the vertical columns 23 arepreferably fixed to the ground by means of a bolt, and a verticalmovement block, which supports a connection frame 25 suitably extendingfrom the up-and-down frame 20 in the width direction so as to move upand down, and a horizontal bar connecting the vertical movement blockare suitably provided on one side of the vertical column 23.

In further preferred embodiments, an up-and-down movement motor 26 asthe carrier drop means is suitably provided on the top of the horizontalcolumn 24, a timing belt 27 as the power transmission means fortransmitting the rotational force of the motor 26 is suitably provided,and a weight balance 28 as a balance means for preferably adjusting theweight and balance of the up-and-down movement frame 20 is suitablyprovided at the bottom thereof.

In other preferred embodiments, a pulley shaft including a pulleyconnected to an output shaft of the motor 6 preferably extends in thelongitudinal direction thereof, and at least one end of the timing belt27 is suitably connected to a connection bar and the other end issuitably connected to the weight balance 28. Accordingly to preferredembodiments of the invention, when the motor 26 rotates in onedirection, the up-and-down movement frame 20 connected to the connectionbar moves up, and the weight balance 28 suitably moves down. Accordingto other embodiments of the invention, when the motor 26 rotates in theother direction, the up-and-down movement frame 20 connected to theconnection bar moves down, and the weight balance 28 preferably movesup.

In other embodiments of the invention, the weight balance 28 ispreferably provided on the opposite side of the up-and-down movementframe 20 with the vertical column 23 preferably interposed therebetween,and a guide roller 29 is preferably installed on one side of the weightbalance 28 to suitably facilitate the up and down movement of the weightbalance 28.

Accordingly, the horizontal movement driving means drives the carrier 12by friction when the carrier 12 horizontally moves on the welding line17 and the return line 18. In particular preferred embodiments, thehorizontal movement driving means drives the carrier 12 preferably byusing an induction motor 31 suitably equipped with a decelerator 30 andbringing a friction bar 34 of the carrier 12 into contact between afriction wheel 32, that is, for example, rotatably provided on the topof the decelerator 30, and an idle wheel 33, that is in other preferredembodiments rotatably provided on the opposite side thereof.

In exemplary embodiments, a rotation shaft of the friction wheel 32 isconnected to an output shaft of the decelerator 30. Accordingly, theinduction motor 31, the decelerator 30, and the friction wheel 32 arepreferably provided on one side of a first member 35, and the idle wheel33 is preferably provided on one side of a second member 36. Inexemplary embodiments, center portions of the first and second members35 and 36 are connected by a hinge pin 37, and the other sides of thefirst and second members 35 and 36 are preferably connected by a bolt 39and a nut 40 with a spring 38 inserted therebetween.

According to certain embodiments of the invention, when the bolt 39 isscrewed into the nut 40, the spring 38 is suitably compressed, and thusthe gap between the first and second members 35 and 36 on spring side issubstantially closed based on the hinge pin 37 and the gap between thefriction wheel 32 and the idle wheel 33 on the opposite side is suitablywidened. In other exemplary embodiments, when the bolt 39 is unscrewedfrom the nut 40, the spring 38 is suitably restored, and thus the gapbetween the first and second members 35 and 36 on the spring side iswidened based on the hinge pin 37 and the gap between the friction wheel32 and the idle wheel 33 on the opposite side is closed.

According to embodiments of the invention as described herein, since thefriction wheel 32 and the idle wheel 33 are in frictional contact withthe friction bar 34 due to the elastic force of the spring by suitablyadjusting the bolt 39 and the nut 40, the rotational force of theinduction motor 31 is suitably transferred to the friction bar 34through the friction wheel 32 and the idle wheel 33, thus enabling thecarrier 12 to horizontally move.

According to other further embodiments, since the present inventionenables the carrier 12 to horizontally move in a frictional contactmanner, it is possible to suitably reduce the number of motors and thecapacity of the inverters for controlling the motors and thus,preferably, to more accurately and rapidly control the speed of thefriction bar 34 by the motor control, compared with the conventionalnon-contact manner.

In preferred embodiments, the carrier 12, preferably including a jigunit 43 for restricting the panel, is a suitably means for transferringthe restricted panel to each process. In other further embodiments, thefriction bar 34 is suitably attached to the bottom of the carrier 12 soas to transfer the frictional force, i.e., the driving force, by thehorizontal movement driving means 11. For example, in certain exemplaryembodiments, the friction bar 34 is detachably mounted to the carrier 12to suitably improve the handling of the carrier 12 and facilitate thesafekeeping of the carrier 12. For example, in preferred embodiments,the friction bar 34 may be suitably attached to both sides of the bottomportion of the carrier 12 by a fixing pin 44.

In other embodiments, the welding line 17 in accordance with the presentinvention in which a key welding process is suitably performed by awelding robot 16 is preferably provided on the first floor, and thereturn line 18 is disposed on the top of the welding line 17 so as toimprove the workability of the welding robot 16.

In still other further embodiments, on the welding line 17 and thereturn line 18, first and second driving rails 41 and 42 are preferablyprovided parallel to each other in the horizontal direction on the topand bottom of a plurality of rectangular frames 45 suitably provided atregular intervals such that the carrier 12 may move along the first andsecond driving rails 41 and 42.

Accordingly, in preferred embodiments, the rectangular frames 45 arepreferably provided in the vertical direction, the return line 18 isdisposed on the rectangular frames 45, and the welding line 17 ispreferably disposed below the rectangular frames 45.

In further exemplary embodiments, the welding line 17 may be suitablydivided into a loading section (B) where the carrier 12 is loaded, awelding section (C) where the panel is welded by the welding robot 16,and an unloading section (D) where the welded panel is unloaded. Inother further embodiments, the return line 18 may be suitably dividedinto a first return section where the carrier 12, from which the panelhas been unloaded, moves upward, and a second return section where thecarrier 12 moves from the first return section to the loading section.

In certain embodiments of the invention, the loading section (B), thewelding section (C), and the unloading section (D) of the welding line17 are preferably arranged in a straight line, and the first and secondreturn sections of the return line 18 are suitably provided on differentfloors.

In other embodiments of the invention, a second driving rail 42′ of thefirst return section is preferably supported by a vertically extendingframe 46 provided on or near the top of the rectangular frame 45 in thevertical direction, and thus the height of the second driving rail 42′is larger than that of the second return section as much as the heightof the vertically extending frame 46.

Accordingly, in certain embodiments of the invention, the second drivingrail 42′ of the first return section preferably has a greater heightthan that of the second return section in order to prevent an arm 47 ofthe welding robot 16 during up and down movement from being interruptedby the second driving rail 42 of the second return section having thesame height as the second driving rail 42′ of the first return section.

For example, the second driving rail 42 of the first return section ispreferably moved upward so that the arm 47 of the welding robot 16 mayfreely move in the welding section (C) and, since the second returnsection is substantially out of the working radius of the welding robot16, the second driving rail 42 is preferably provided on the top of therectangular frame 45.

In preferred embodiments, the carrier 12 includes, but is not limitedto, a second driving wheel 48 preferably mounted on the top side thereofto drive along the second driving rail 42′ of the first return section,and a first driving wheel 21 preferably mounted on the bottom side todrive along the introduction portion of the first return section, thesecond driving rail 42 of the second return section, and the firstdriving rail 41 of the welding line 17.

In exemplary embodiments, the horizontal movement driving means ispreferably provided at each section of the welding line 17 and thereturn line 18, and the drop lifter 10 is provided at a line panelloading side (A) so as to move the carrier 12 from the return line 18 tothe welding line 17 and preferably employs a carrier changing robot 15as a carrier lift means to lift the carrier, from which the panel hasbeen unloaded, to the return line 18.

In certain examples, the carrier changing robot 15 includes, but is notlimited to, a carrier handling hanger 50 mounted on the arm portion inorder to preferably move the carrier 12, from which the panel has beenunloaded, to the return line 18 and move another carrier 12 of adifferent vehicle type from the carrier loading stand 13 to the returnline 18.

Preferably, the carrier loading stand 13 is a place where the carriers12 classified by vehicle type are loaded and kept and includes avertical frame 54 provided in the vertical direction and a horizontalframe 55 supported in the horizontal direction on the top and bottomportions of the vertical frame 54, in which a fixing pin 56 for fixingthe carrier 12 is provided on the horizontal frame 55.

According to further embodiments, the carriers 12 are preferably kept onthe first and second floors of the carrier loading stand 13, and thusprovide excellent space utilization. According to other embodiments, thecarrier 12 is handled by the carrier changing robot 15, and preferablythe carrier loading stand 13 does not require any separate device forhandling the carrier 12, and thus the system is suitably simplified andthe manufacturing cost is reduced.

According to exemplary embodiments of the invention, the operation orderof the floor production system in accordance with the invention asdescribed herein, will be set forth below.

(1) After the carrier 12 is returned to the guide rail 19 of the droplift 10 through the second return section of the return line 18, thepanel to be welded is preferably loaded on the carrier 12 at the A-side.

(2) With the operation of the up-and-down movement motor 26, the timingbelt 27 suitably rotates in one direction, and thus the up-and-downframe 20 of the drop lifter 10 moves down. Then, with the operation ofthe motor 26 in the horizontal movement driving means of the drop lifter10, the friction wheel 32 rotates, and thus the carrier 12 is moved tothe loading section (B) of the welding line 17 by the frictional forceof the friction wheel 32 and the friction bar 34. Subsequently, thecarrier 12 enters the welding section (C) so that the welding robot 16performs the key welding process, thus completing a front floor.

(3) After completion of the key welding process, when the inductionmotor 31 in the horizontal movement driving means at the welding section(C) operates so that the friction wheel 32 rotates, the carrier 12 ispreferably moved to the unloading section (D) of the welding line 17 bythe frictional force of the friction wheel 32 and the friction bar 34.Subsequently, the unloading robot 14 transfers the completed front floorto the following line.

(4) After the front floor is unloaded, the carrier 12 is preferablymoved up to the first return section of the return line 18 by thecarrier changing robot 15 and, when the induction motor 31 in thehorizontal movement driving means at the welding section (C) operates sothat the friction wheel 32 rotates, the carrier 12 is preferably movedto the second return section of the return line 18 by the frictionalforce of the friction wheel 32 and the friction bar 34. At this time,the up-and-down frame 20 of the drop lifter 10 returned to the originalposition receives the carrier 12 from the second return section and ismoved down by the carrier drop means.

Here, the carrier changing robot 15 determines the vehicle type of thecarrier 12 and, if the carrier 12 is needed to be changed, suitablychanges the carrier 12 with another carrier 12 of the correspondingvehicle type in the carrier loading stand 13.

Then, in preferred embodiments of the invention as described herein, theabove-described operations in the order of drop lifter 10→welding line17 [loading (B), welding (C), and unloading (D)]→return line 18 arecontinuously repeated to produce the front floors.

In certain embodiments, the working line is provided at the top and thereturn line is provided at the bottom in the conventional system, andaccordingly, the working height of the robots is suitably increased andall of the equipment is installed at high position, and thus themaintenance and reliability are lessened.

Accordingly, in preferred embodiments, the present invention preferablyplaces the key welding process on the first floor so as to ensure thesafety and stability of the system.

In further embodiments, the present invention preferably features acenter floor and a rear floor besides the front floor.

As described herein, the vehicle floor production system in accordancewith the present invention has, but is not limited to, the followingeffects.

According to preferred embodiments of the invention, the rotationalforce of the motor is suitably transferred to the carrier by thefrictional contact between the friction bar attached to the carrier andthe friction wheel mounted on the line. Accordingly, it is possible toreduce the manufacturing cost, compared with the conventional linearmotor by the non-contact power transmission.

Moreover, in other further embodiments, since the welding line ispreferably provided at the bottom of the system and the return line ispreferably provided at the top to reduce the working height, accordingto other further embodiments, it is possible to ensure the safety andreliability of the system.

According to exemplary embodiments, a portion of the return line ismoved substantially upward and the driving wheels of the carrier areprovided in two stages, thus it is possible in other further embodimentsto ensure the working space of the welding robot.

In further embodiments, the friction bar is detachably mounted to thecarrier, thus it is possible to improve the handling of the carrier andfacilitate the safekeeping of the carrier.

In other further embodiments, the robot is handled by the robot, thusthe carrier loading stand preferably does not require any separatedevice for handling the carrier, thus simplifying the system andreducing the manufacturing cost.

The invention has been described in detail with reference to preferredembodiments thereof. However, it will be appreciated by those skilled inthe art that changes may be made in these embodiments without departingfrom the principles and spirit of the invention, the scope of which isdefined in the appended claims and their equivalents.

1. A vehicle floor production system comprising: a return line and awelding line provided parallel to each other on the top and bottom of aframe so as to move a carrier; a carrier drop means including a guiderail provided on the top thereof to load a panel on the carrier receivedfrom the return line and move the carrier to the welding line; ahorizontal movement driving means for moving the carrier in thehorizontal direction on the return line, the welding line and thecarrier drop means by frictional force; a welding robot for welding thepanel moved by the horizontal movement driving means in a predeterminedsection of the welding line; and a carrier changing robot including acarrier handling hanger provided at an end of an arm portion thereof tomove the carrier from the welding line to the return line aftercompletion of the panel welding process.
 2. The system of claim 1,wherein the return line and the welding line include first and seconddriving wheels provided to move the carrier, and a portion of the firstdriving wheel of the return line is moved upward and mounted to ensure aworking space of a welding robot.
 3. The system of claim 1, wherein thecarrier drop means comprises: a frame including a guide rail provided onthe top thereof; a vertical column for supporting the frame so as toslidably move in the up and down direction; a horizontal column forconnecting the top portion of the vertical column; an up-and-downmovement motor provided on the top of the horizontal column; a powertransmission means for transmitting the rotational force of theup-and-down movement motor to the frame; and a weight balance connectedto an end portion of the power transmission means and moving up and downat the opposite side of the frame to adjusting the balance.
 4. Thesystem of claim 3, wherein the power transmission means comprises: arotation transmission shaft connected to an output shaft of the motorand including a pulley provided on the outer surface thereof; and abelt, of which one end is connected to the frame and a middle portion isengaged with the pulley so as to transmit the rotational force of themotor.
 5. The system of claim 4, wherein the horizontal movement drivingmeans comprises: a friction bar fixedly provided in the longitudinaldirection of the carrier; a horizontal movement motor and a deceleratorprovided on the frame on which the carrier drop means, the return line,and the welding line are provided; a friction wheel driven by thehorizontal movement motor and the decelerator and transmitting therotational force of the motor by being contact with one side of thefriction bar; a guide wheel rotatably provided on both sides of thefriction bar to be in contact therewith; and an idle wheel provided onthe opposite side of the friction bar to be in contact therewith.
 6. Thesystem of claim 5, wherein the horizontal movement driving means furthercomprises: a hinge pin rotatably supported to the frame; first andsecond rotational members, of which center portions are rotatablyconnected to the hinge pin; and a gap adjusting bolt and a springinserted between end portions of the first and second rotationalmembers, wherein the motor, the decelerator, and the friction wheel areprovided on one side of the first rotational member, and the idle wheelis provided on one side of the second rotational member, and wherein thefriction wheel and the idle wheel are in frictional contact with thefriction bar by the elastic force of the spring, and a gap between thefirst and second rotational members is adjusted by the gap adjustingbolt.
 7. The system of claim 1, further comprising a carrier loadingstand capable of loading carriers classified by vehicle type, whereinthe carrier loading stand includes a vertical frame provided in thevertical direction and a loading frame provided in the horizontaldirection on the top and bottom thereof, and a carrier of the weldingline and a carrier of the carrier loading stand are changed by thecarrier changing robot.
 8. A vehicle floor production system comprising:a return line and a welding line to move a carrier; a carrier dropmeans; a horizontal movement driving means; and a welding robot forwelding the panel moved by the horizontal movement driving means in apredetermined section of the welding line.
 9. The vehicle floorproduction system of claim 8, further comprising a carrier changingrobot including a carrier handling hanger provided at an end of an armportion thereof to move the carrier from the welding line to the returnline after completion of the panel welding process.
 10. The vehiclefloor production system of claim 8, wherein the horizontal movementdriving means moves the carrier in the horizontal direction on thereturn line, the welding line and the carrier drop means by frictionalforce.
 11. The vehicle floor production system of claim 8, wherein thereturn line and a welding line provided parallel to each other on thetop and bottom of a frame so as to move a carrier
 12. The vehicle floorproduction system of claim 8, wherein the carrier drop means includes aguide rail provided on the top thereof to load a panel on the carrierreceived from the return line and move the carrier to the welding line.13. A motor vehicle comprising the vehicle floor production system ofclaim
 1. 14. A motor vehicle comprising the vehicle floor productionsystem of claim 8.